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Title: The role of remote sensing in assessing the impact of climate variability on vegetation dynamics in Europe
Author: Gouveia, Célia Marina Pedroso, 1970-
Advisor: Câmara, Carlos Portugal da, 1957-
Trigo, Ricardo M., 1967-
Keywords: Detecção remota
Dinâmica da vegetação
Teses de doutoramento - 2008
Defense Date: 2008
Abstract: The study aims at investigating the relationship between climate variability and vegetation dynamics by combining meteorological and remote-sensed information. The vegetation response to both precipitation and temperature in two contrasting areas (Northeastern Europe and the Iberian Peninsula) of the European continent is analysed and special attention is devoted to the impact of the North Atlantic Oscillation (NAO) on the vegetative cycle in the two regions which is assessed taking into account the different land cover types and the respective responses to climate variability. An analysis is performed of the impact of climate variability on wheat yield in Portugal and. the role of NAO and of relevant meteorological variables (net solar radiation, temperature and precipitation) is investigated. Using spring NDVI and NAO in June as predictors, a simple regression model of wheat yield is built up that shows a general good agreement between observed and modelled wheat yield values. The severity of a given drought episode in Portugal is assessed by evaluating the cumulative impact over time of negative anomalies of NDVI. Special attention is devoted to the drought episodes of 1999, 2002 and 2005. While in the case of the drought episode of 1999 the scarcity of water in the soil persisted until spring, the deficit in greenness in 2005 was already apparent at the end of summer. Although the impact of dry periods on vegetation is clearly noticeable in both arable land and forest, the latter vegetation type shows a higher sensitivity to drought conditions. Persistence of negative anomalies of NDVI was also used to develop a procedure aiming to identify burned scars in Portugal and then assess vegetation recovery over areas stricken by large wildfires. The vulnerability of land cover to wildfire is assessed and a marked contrast is found between forest and shrubland vs. arable land and crops. Vegetation recovery reveals to strongly depend on meteorological conditions of the year following the fire event, being especially affected in case of a drought event.
Description: Tese de doutoramento em Ciências Geofísicas e da Geoinformação (Detecção Remota), apresentada à Universidade de Lisboa através da Faculdade de Ciências, 2008
Appears in Collections:FC - Teses de Doutoramento

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